define(function(require, exports, module){
	var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
	var base64DecodeChars = new Array(-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1,
			63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1,
			0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
			20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31,
			32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49,
			50, 51, -1, -1, -1, -1, -1);
	return {
	
		/**
		 * base64编码
		 * 
		 * @param {Object}
		 *            str
		 */
		base64encode: function(str) {
			var out, i, len;
			var c1, c2, c3;
			len = str.length;
			i = 0;
			out = "";
			while (i < len) {
				c1 = str.charCodeAt(i++) & 0xff;
				if (i == len) {
					out += base64EncodeChars.charAt(c1 >> 2);
					out += base64EncodeChars.charAt((c1 & 0x3) << 4);
					out += "==";
					break;
				}
				c2 = str.charCodeAt(i++);
				if (i == len) {
					out += base64EncodeChars.charAt(c1 >> 2);
					out += base64EncodeChars.charAt(((c1 & 0x3) << 4)
							| ((c2 & 0xF0) >> 4));
					out += base64EncodeChars.charAt((c2 & 0xF) << 2);
					out += "=";
					break;
				}
				c3 = str.charCodeAt(i++);
				out += base64EncodeChars.charAt(c1 >> 2);
				out += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4));
				out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >> 6));
				out += base64EncodeChars.charAt(c3 & 0x3F);
			}
			return out;
		},
		
		/**
		 * base64解码
		 * 
		 * @param {Object}
		 *            str
		 */
		base64decode: function(str) {
			var c1, c2, c3, c4;
			var i, len, out;
			len = str.length;
			i = 0;
			out = "";
			while (i < len) {
				/* c1 */
				do {
					c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
				} while (i < len && c1 == -1);
				if (c1 == -1)
					break;
				/* c2 */
				do {
					c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
				} while (i < len && c2 == -1);
				if (c2 == -1)
					break;
				out += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));
				/* c3 */
				do {
					c3 = str.charCodeAt(i++) & 0xff;
					if (c3 == 61)
						return out;
					c3 = base64DecodeChars[c3];
				} while (i < len && c3 == -1);
				if (c3 == -1)
					break;
				out += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2));
				/* c4 */
				do {
					c4 = str.charCodeAt(i++) & 0xff;
					if (c4 == 61)
						return out;
					c4 = base64DecodeChars[c4];
				} while (i < len && c4 == -1);
				if (c4 == -1)
					break;
				out += String.fromCharCode(((c3 & 0x03) << 6) | c4);
			}
			return out;
		},
		
		/**
		 * utf16转utf8
		 * 
		 * @param {Object}
		 *            str
		 */
		utf16to8: function(str) {
			var out, i, len, c;
			out = "";
			len = str.length;
			for (i = 0; i < len; i++) {
				c = str.charCodeAt(i);
				if ((c >= 0x0001) && (c <= 0x007F)) {
					out += str.charAt(i);
				} else if (c > 0x07FF) {
					out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));
					out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F));
					out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
				} else {
					out += String.fromCharCode(0xC0 | ((c >> 6) & 0x1F));
					out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
				}
			}
			return out;
		},
		
		/**
		 * utf8转utf16
		 * 
		 * @param {Object}
		 *            str
		 */
		utf8to16: function(str) {
			var out, i, len, c;
			var char2, char3;
			out = "";
			len = str.length;
			i = 0;
			while (i < len) {
				c = str.charCodeAt(i++);
				switch (c >> 4) {
				case 0:
				case 1:
				case 2:
				case 3:
				case 4:
				case 5:
				case 6:
				case 7:
					// 0xxxxxxx
					out += str.charAt(i - 1);
					break;
				case 12:
				case 13:
					// 110x xxxx 10xx xxxx
					char2 = str.charCodeAt(i++);
					out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
					break;
				case 14:
					// 1110 xxxx10xx xxxx10xx xxxx
					char2 = str.charCodeAt(i++);
					char3 = str.charCodeAt(i++);
					out += String.fromCharCode(((c & 0x0F) << 12)
							| ((char2 & 0x3F) << 6) | ((char3 & 0x3F) << 0));
					break;
				}
			}
			return out;
		}
	};
});

